In answer to the original question and the three options, I would say the inevitable answer is to raise the ticket cost. I think you have to decide what is special about LEL and calculate an entry fee that realistically covers the cost of delivering that experience, rather than starting with a price and trying to change LEL to meet that constraint.
My simplistic Goldilocks analysis is that paying £360 was a no-brainer for what was provided, if LEL cost £1000 I would be passing, but if the 2025 cost was nearer £500 I would probably think a bit more carefully but still conclude it was a good deal, considering how costs have risen (and will continue to rise). I just checked Ride Across Britain, and even allowing for the fact it is a nine day event, it is currently an eye watering £1850, or £2450 if you don't want to sleep in a tent! Even the Pan Celtic is £445, and you don't actually seem to get much that is practically useful included in that fee.
I think LEL (and Audax generally) is still gaining new social media exposure and reaching new people outside the traditional Audax community, so I would guess that the entry could still grow a bit (perhaps closer to 2000?). However, I agree with some of the other comments that there is an increasingly crowded market for ultra distance rides, and LEL is unlikely to "poach" huge numbers of people from these other events. For example, I think RAB has a particular clientele because of its strong corporate links and subsidised fund raising model. A lot of people will be entering in work backed company teams and raising sponsorship for specific charities, and the event confers specific kudos in that sphere. You won't get lots of RAB entrants opting for LEL instead because it is cheaper. I think many of the people who participate in events like the Pan Celtic/TCR are a bit more "indie" and would perceive LEL as old school and more "roadie" in character (although these are generalisations and a fair number of people do straddle both types of events).
I assume it would be difficult to tweak the catering to significantly save costs, and I can't imagine that it would be possible to provide all options at all times without huge overstocking and consequent waste. Riding in the sub 100 hour group, I can think of one control where I found the options were a bit limited one morning, but it wasn't a problem and I still got a good enough feed to keep me turning the pedals. I also don't really think there are huge numbers of people greedily hoovering up extra dinners that they don't need, and running a meal ticket system would just be another administrative headache for the volunteer force.
I don't think encouraging support vehicles is a good idea. Adding sufficient cars and motorhomes to significantly help the budget would introduce problems with parking, traffic management and safety when entering and leaving controls, and en-route. I had a support vehicle pass me in the small hours on a narrow road approaching the Moorfoots last year; I know they weren't supposed to be on the course, but people will do it, and you won't be able to police them. I think being self supported (outside controls) is an important part of LEL and should remain the default for most riders.
Perhaps one area where you could raise more revenue would be upselling the spot tracker hire. Personally, I have no desire whatsoever to be tracked while I'm out for a bike ride, but I know lots of people love dot watching and being dot watched, so there is probably scope to charge a bit more and grow that as an optional extra? There is a downside that spot tracking encourages the perception of LEL as an "Audax race", which is not ideal.
I don't yet know if I will enter again in 2025, but my experience of 2022 was overwhelmingly positive and I would just say thank you again for all the hard work of you and your volunteers. I'm interested to see the new route, but I really hope it has not been flattened too much. I thought Yorkshire and the Pennines were great, and a ride like LEL needs a proper bit of climbing somewhere, rather than just distance, in order to give it flavour!